X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=doc%2Fstatistics.texi;h=789e37bc9591a9f56bb09361c6a4ddc1fb0160ce;hb=3a8f3341eb7a7f2a580ce7120bb96973df0b9f67;hp=e366468ee4bc2ad3ab74c541d6618b2f034bbda0;hpb=c93bf9192871e358daf5f30d537a24eb2c6c5aad;p=pspp diff --git a/doc/statistics.texi b/doc/statistics.texi index e366468ee4..789e37bc95 100644 --- a/doc/statistics.texi +++ b/doc/statistics.texi @@ -8,6 +8,7 @@ far. * DESCRIPTIVES:: Descriptive statistics. * FREQUENCIES:: Frequency tables. * EXAMINE:: Testing data for normality. +* GRAPH:: Plot data. * CORRELATIONS:: Correlation tables. * CROSSTABS:: Crosstabulation tables. * FACTOR:: Factor analysis and Principal Components analysis. @@ -194,9 +195,13 @@ For instance, @subcmd{/NTILES=4} would cause quartiles to be reported. The @subcmd{HISTOGRAM} subcommand causes the output to include a histogram for each specified numeric variable. The X axis by default ranges from the minimum to the maximum value observed in the data, but the @subcmd{MINIMUM} -and @subcmd{MAXIMUM} keywords can set an explicit range. Specify @subcmd{NORMAL} to -superimpose a normal curve on the histogram. Histograms are not -created for string variables. +and @subcmd{MAXIMUM} keywords can set an explicit range. The number of +bins are 2IQR(x)n^-1/3 according to the Freedman-Diaconis rule. (Note that +@cmd{EXAMINE} uses a different algorithm to determine bin sizes.) +Histograms are not created for string variables. + +Specify @subcmd{NORMAL} to superimpose a normal curve on the +histogram. @cindex piechart The @subcmd{PIECHART} subcommand adds a pie chart for each variable to the data. Each @@ -250,7 +255,7 @@ factors which tell @pspp{} how to break down the analysis for each dependent variable. Following the dependent variables, factors may be specified. -The factors (if desired) should be preceeded by a single @subcmd{BY} keyword. +The factors (if desired) should be preceded by a single @subcmd{BY} keyword. The format for each factor is @display @var{factorvar} [BY @var{subfactorvar}]. @@ -288,6 +293,10 @@ normal distribution, whilst the spread vs.@: level plot can be useful to visuali how the variance of differs between factors. Boxplots will also show you the outliers and extreme values. +@subcmd{HISTOGRAM} uses Sturges' rule to determine the number of +bins, as approximately 1 + log2(n). (Note that @cmd{FREQUENCIES} uses a +different algorithm to find the bin size.) + The @subcmd{SPREADLEVEL} plot displays the interquartile range versus the median. It takes an optional parameter @var{t}, which specifies how the data should be transformed prior to plotting. @@ -309,10 +318,10 @@ If the @subcmd{/COMPARE} subcommand is omitted, then @pspp{} behaves as if The @subcmd{ID} subcommand is relevant only if @subcmd{/PLOT=BOXPLOT} or @subcmd{/STATISTICS=EXTREME} has been given. -If given, it shoule provide the name of a variable which is to be used +If given, it should provide the name of a variable which is to be used to labels extreme values and outliers. Numeric or string variables are permissible. -If the @subcmd{ID} subcommand is not given, then the casenumber will be used for +If the @subcmd{ID} subcommand is not given, then the case number will be used for labelling. The @subcmd{CINTERVAL} subcommand specifies the confidence interval to use in @@ -375,6 +384,53 @@ specified for which there are many distinct values, then @cmd{EXAMINE} will produce a very large quantity of output. +@node GRAPH +@section GRAPH + +@vindex GRAPH +@cindex Exploratory data analysis +@cindex normality, testing + +@display +GRAPH + /HISTOGRAM = @var{var} + /SCATTERPLOT [(BIVARIATE)] = @var{var1} WITH @var{var2} [BY @var{var3}] + [ /MISSING=@{LISTWISE, VARIABLE@} [@{EXCLUDE, INCLUDE@}] ] + [@{NOREPORT,REPORT@}] + +@end display + +The @cmd{GRAPH} produces graphical plots of data. Only one of the subcommands +@subcmd{HISTOGRAM} or @subcmd{SCATTERPLOT} can be specified, i.e. only one plot +can be produced per call of @cmd{GRAPH}. The @subcmd{MISSING} is optional. + +@cindex scatterplot + +The subcommand @subcmd{SCATTERPLOT} produces an xy plot of the data. The different +values of the optional third variable @var{var3} will result in different colours and/or +markers for the plot. The following is an example for producing a scatterplot. + +@example +GRAPH + /SCATTERPLOT = @var{height} WITH @var{weight} BY @var{gender}. +@end example + +This example will produce a scatterplot where @var{height} is plotted versus @var{weight}. Depending +on the value of the @var{gender} variable, the colour of the datapoint is different. With +this plot it is possible to analyze gender differences for @var{height} vs.@: @var{weight} relation. + +@cindex histogram + +The subcommand @subcmd{HISTOGRAM} produces a histogram. Only one variable is allowed for +the histogram plot. +For an alternative method to produce histograms @pxref{EXAMINE}. The +following example produces a histogram plot for the variable @var{weight}. + +@example +GRAPH + /HISTOGRAM = @var{weight}. +@end example + @node CORRELATIONS @section CORRELATIONS @@ -500,7 +556,7 @@ The @subcmd{FORMAT} subcommand controls the characteristics of the crosstabulation tables to be displayed. It has a number of possible settings: -@itemize @asis +@itemize @w{} @item @subcmd{TABLES}, the default, causes crosstabulation tables to be output. @subcmd{NOTABLES} suppresses them. @@ -603,10 +659,10 @@ following bugs: @itemize @bullet @item -Significance of symmetric and directional measures is not calculated. +Significance of some symmetric and directional measures is not calculated. @item -Asymptotic standard error is not calculated for asymmetric lambda, -Goodman and Kruskal's tau, or symmetric Somers' d. +Asymptotic standard error is not calculated for +Goodman and Kruskal's tau or symmetric Somers' d. @item Approximate T is not calculated for symmetric uncertainty coefficient. @end itemize @@ -629,7 +685,7 @@ FACTOR VARIABLES=@var{var_list} [ /EXTRACTION=@{PC, PAF@}] - [ /ROTATION=@{VARIMAX, EQUAMAX, QUARTIMAX, NOROTATE@}] + [ /ROTATION=@{VARIMAX, EQUAMAX, QUARTIMAX, PROMAX[(@var{k})], NOROTATE@}] [ /PRINT=[INITIAL] [EXTRACTION] [ROTATION] [UNIVARIATE] [CORRELATION] [COVARIANCE] [DET] [KMO] [SIG] [ALL] [DEFAULT] ] @@ -653,9 +709,13 @@ If @subcmd{PAF} is specified, then Principal Axis Factoring is used. By default Principal Components Analysis will be used. The @subcmd{/ROTATION} subcommand is used to specify the method by which the extracted solution will be rotated. -Three methods are available: @subcmd{VARIMAX} (which is the default), @subcmd{EQUAMAX}, and @subcmd{QUARTIMAX}. -If don't want any rotation to be performed, the word @subcmd{NOROTATE} will prevent the command from performing any -rotation on the data. Oblique rotations are not supported. +Three orthogonal rotation methods are available: +@subcmd{VARIMAX} (which is the default), @subcmd{EQUAMAX}, and @subcmd{QUARTIMAX}. +There is one oblique rotation method, @i{viz}: @subcmd{PROMAX}. +Optionally you may enter the power of the promax rotation @var{k}, which must be enclosed in parentheses. +The default value of @var{k} is 5. +If you don't want any rotation to be performed, the word @subcmd{NOROTATE} will prevent the command from performing any +rotation on the data. The @subcmd{/METHOD} subcommand should be used to determine whether the covariance matrix or the correlation matrix of the data is to be analysed. By default, the correlation matrix is analysed. @@ -1078,7 +1138,7 @@ outside the specified range are excluded from the analysis. The @subcmd{/EXPECTED} subcommand specifies the expected values of each category. There must be exactly one non-zero expected value, for each observed -category, or the @subcmd{EQUAL} keywork must be specified. +category, or the @subcmd{EQUAL} keyword must be specified. You may use the notation @subcmd{@var{n}*@var{f}} to specify @var{n} consecutive expected categories all taking a frequency of @var{f}. The frequencies given are proportions, not absolute frequencies. The @@ -1329,7 +1389,7 @@ of variable preceding @code{WITH} against variable following The @subcmd{/WILCOXON} subcommand tests for differences between medians of the variables listed. The test does not make any assumptions about the variances of the samples. -It does however assume that the distribution is symetrical. +It does however assume that the distribution is symmetrical. If the @subcmd{WITH} keyword is omitted, then tests for all combinations of the listed variables are performed. @@ -1493,7 +1553,7 @@ The list of variables must be followed by the @subcmd{BY} keyword and the name of the independent (or factor) variable. You can use the @subcmd{STATISTICS} subcommand to tell @pspp{} to display -ancilliary information. The options accepted are: +ancillary information. The options accepted are: @itemize @item DESCRIPTIVES Displays descriptive statistics about the groups factored by the independent @@ -1665,7 +1725,7 @@ RELIABILITY @end display @cindex Cronbach's Alpha -The @cmd{RELIABILTY} command performs reliability analysis on the data. +The @cmd{RELIABILITY} command performs reliability analysis on the data. The @subcmd{VARIABLES} subcommand is required. It determines the set of variables upon which analysis is to be performed.